1. Field of the Invention
The present invention relates to the field of bit-de-/multiplexing in multicarrier MIMO communication systems (e.g. precoded spatial multiplexing MIMO communication systems using adaptive OFDM). The present invention especially relates to a multicarrier MIMO transmitter and a multicarrier MIMO receiver.
2. Description of the Prior Art
MIMO (multiple input multiple output) communication systems are well known in the art. A MIMO transmitter comprises at least two transmit ports (e.g. antennas) and MIMO receiver comprises at least two receive ports (e.g. antennas). Signals are transmitted from the transmit ports to the receive ports via a communication channel which generally mixes the signals transmitted by a plurality of transmit ports. The MIMO receiver comprises a MIMO detector (MIMO decoder) which “demixes” the received signals and obtains the information comprised in the signals transmitted by the MIMO transmitter. Various kinds of MIMO transmitters are known, e.g. space-time encoded MIMO transmitters, and spatial multiplexing MIMO transmitters with precoding (e.g. eigenbeamforming MIMO transmitters) and without precoding. For each type of MIMO transmitter, a corresponding MIMO receiver is employed. MIMO technology achieves a higher spectral efficiency and higher link reliability. Also, multicarrier modulation schemes like, for example, OFDM (orthogonal frequency division multiplexing) and multicarrier wavelet modulation are well known. MIMO systems have two or more transmission channels. Usually an application has one data source and one data sink. Therefore, the data to be transmitted have to be split (demultiplexed, demuxed) to various transmission channels. At the receiver, the split data received on individual transmission channels need to be combined (multiplexed, muxed) again. This task is called bit-de-/multiplexing for the individual transmission channels. PLC (power line communication or power line carrier) communication systems transmit data using one or more conductors that are regularly used for electric power transmission. Wireless multicarrier MIMO systems use a constant symbol mapping (e.g. QAM mapping) for all carriers. This results in a constant throughput on the individual channels, so the demultiplexing at the transmitter is a static split of the incoming bits to the outgoing bits. At the receiver, the bits will be muxed in a static way again.
It is the object of the present invention to provide for improved multicarrier MIMO transmitters and receivers, especially to provide for an improved robustness of data transmission and/or reduced complexity of data transmission.